This invention relates to an image forming device such as a printer to which it is possible to connect an external device such as a scanner or controller. More particularly, the invention relates to an image forming device to which a plurality of external devices can be connected so that image data from these external devices can be received efficiently and the images printed out.
In the prior art, an image forming device of this kind has a single connector for connecting an external device (a scanner or controller, etc.), and a certain single external device desired by the user can be used upon being connected to this connector.
For example, the user of such an image forming device is required to make an alternative selection between use of a scanner upon connecting the same or user of a network-connected controller upon connecting the same. If the user wises to employ several external devices simultaneously, the user must manually detach the external device from the connector each time and re-connect the connector to the desired external device.
A proposal that has been made in order to eliminate this inconvenience is to allow a printer engine to be monopolized or occupied by any of two or more external devices by having the user change over a switch manually (see Japanese Patent Laid-Open Application No. 2000-332922). Though this proposal does away with the aforementioned troublesome operation of detaching and re-connecting a connector manually, that fact remains that a manual switching operation is required. A further improvement, therefore, is needed.
Accordingly, in order to comply with the above-mentioned need, an object of the present invention is to provide an image forming device in which the number of connectors for connection to external devices is made two or more so that connection to a plurality of external devices is made possible, wherein the image forming device is additionally provided with a selective changeover capability to make possible communication with a plurality of external devices at any time as well as control of each device independently.
A further object of the present invention is to simplify the structure of the image forming device and provide the image forming device in a form in which signals from each of external devices will not be lost.
According to the present invention, which is set forth in aspect 1, the foregoing objects are attained by providing an image forming apparatus characterized by having a printer engine, first and second connectors for connecting the printer engine to first and second external devices, and a control unit having an alternate operation mode in which communication with the first and second external devices is performed alternatingly by changing over communication at a predetermined cycle, the control unit, during communication with either one of the first and second external devices, enabling reception of commands and/or a print-start signal from this external device and refusing reception of commands and a print-start signal from the other external device; and providing an interval in which reception of commands and a print-start signal from both external devices is refused for a predetermined period of time when communication is changed over from one external device to the other external device.
The image forming device according to the present invention communicates with first and second external devices alternatingly by changing over between these devices automatically at a predetermined cycle, thereby making it possible to receive commands and/or a print-start signal from an external device during communication therewith. By virtue of such an alternate operation mode, a single image forming device can be used with facility by a plurality of external devices by allowing it to be monopolized or exclusive by the external devices when appropriate. Furthermore, when the above-mentioned changeover in communication is made, an interval in which reception of commands and a print-start signal from both external devices is refused for a predetermined period of time is provided, thereby preventing loss of commands or a print-start signal (reception error), which can occur at the time of changeover.
According to the present invention set forth in aspect 2, the image forming device described in aspect 1 is characterized in that when a print-start signal is received from the one external device during communication therewith, a transition is made to an exclusive operation mode in which the printer engine is monopolized or occupied by this external device.
Furthermore, according to the present invention set forth in aspect 3, the image forming device described in aspect 2 is characterized in that the printer engine continues to be monopolized by the one external device for a predetermined period of time following the end of printing, the exclusive operation mode continues if a new print-start signal is issued within this predetermined period of time, and a transition is made to the alternate operation mode if a new print signal is not issued within the predetermined period of time.
Thus, if the printer engine receives a print-start signal from either of the external devices during communication therewith, a transition is made to the exclusive operation mode so that the printer engine may receive image data or the like from this external device and perform printing. For a predetermined period of time following the end of such printing, the printer engine continues to be monopolized by this external device and stands by for issuance of a new print-start signal from this external device. This is desirable in that operation is made more nimble as when printing is performed in successive fashion.
Furthermore, according to the present invention set forth in aspect 4, the image forming device described in aspect 1 is characterized in that when a specific command is received from the one external device during communication therewith, a transition is made to an exclusive operation mode in which the printer engine is monopolized by this external device.
Furthermore, according to the present invention set forth in aspect 5, the image forming device described in aspect 4 is characterized in that the exclusive operation mode is cancelled and a transition is made to the alternate operation mode if a print-start signal is not issued from the external device within a predetermined period of time following transition to the exclusive operation mode.
In the image forming device set forth in aspects 4 and 5, the transition is made to the exclusive operation mode when the printer engine receives a specific command signal from either of the external devices during communication therewith. The printer engine then stands by for a predetermined period of time in order to receive a print-start signal from this external device. If a print-start signal is not issued within this predetermined period of time, the exclusive operation mode based upon this external device is cancelled and a transition is made to the alternate operation mode in order to receive the next command signal.
According to the present invention set forth in aspect 6, the image forming device described in aspects 1 to 5 is characterized in that the exclusive operation mode continues if a new print-start signal is issued within a predetermined period of time following the end of printing, and a transition is made to the alternate operation mode if a new print-start signal is not issued within this predetermined period of time.
According to the present invention set forth in aspect 7, the image forming device described in aspects 1 to 5 is characterized by further provision of selection means capable of specifying freely whether the printer engine is monopolized or occupied by the first external device or the second external device.
According to the present invention set forth in aspect 8, the image forming device described in aspects 1 to 7 is characterized in that the first and second external devices are a scanner and a controller.
According to the present invention, which is set forth in aspect 9, the foregoing objects are attained by providing an image forming apparatus characterized by having a printer engine, first and second connectors for connecting the printer engine to first and second external devices, and a control unit having an alternate operation mode in which communication with the first and second external devices is performed alternatingly by changing over communication at a predetermined cycle, the control unit issuing a busy signal indicating whether the printer engine is capable of receiving a command from each external device and a request signal indicating whether the printer engine is capable of receiving a print-start signal from each external device; notifying, while the printer engine communicates with one of the external devices, the other external device by the busy signal and the request signal that a command and print-start signal cannot be received from this other external device; following notification, notifying both the first and second external devices for a predetermined period of time that a command and print-start signal cannot be received; then, following another predetermined period of time, communicating with the other external device and notifying the one external device by the busy signal and the request signal that a command and print-start signal cannot be received from this one external device; and repeating this operation at a predetermined cycle.